Transversus Abdominus and Its Role in Lumbar Spinal Stabilization

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Transversus Abdominus and Its Role in Lumbar Spinal Stabilization

Transversus Abdominus and its Role in Lumbar Spinal Stabilization 

Spinal stability is dependent upon three sub-systems: the active or contractile system, the passive or non-contractile system and the neural control system. (Panjabi, 1992). If dysfunction is present in any one or a combination of these sub-systems, the stabilizing capacity of the spine will be compromised and painful movement more likely to occur. While all muscles contribute to spinal stability and movement, some are better suited than others to provide dynamic stability. In the lumbar spine (L/S), the deeper muscles, close to the axis of joint motion, with a predominance of Type I muscle fibers, have proven more effective as stabilizers than the larger, more superficially located lumbar spinal muscles.

Research has shown that: 1) people with low back pain (LBP) present with atrophy and altered activation of the deep spinal muscles when compared with persons without LBP (Hodges et al., 1996; Hides et al., 1994) and 2) the deep spinal muscles play a key role in developing inter-segmental motion stiffness which translates into improved dynamic control of the spine (Hodges et al., 2003).

Transversus Abdominus (TA) is an important dynamic stabilizer of the L/S. TA is able to directly increase intra-abdominal pressure which converts the trunk into a more solid cylinder. This reduces compression and shear forces acting on the L/S and transmits them over a wider area (Twomey & Taylor, 1987). TAs attachment to the thoracolumbar fascia further increases its ability to stabilize the L/S.

The success of specific spinal stabilization training for TA and other deep muscles lies in: 1) teaching clients to activate the dysfunctional muscle in isolation of other muscles; 2) effectively retraining slow twitch muscle fiber function through isometric contractions (low loads, sustained hold times); 3) repetition: to aid motor reprogramming; 4) teaching co-contraction of the target muscle, first with other deep muscles, then the global muscle network and 5) training carryover for physical and functional tasks of increasing levels of difficulty.

“Exercises that target the deep abdominal muscles with minimal external loading in the spine have been shown to be effective in increasing lumbar stability, thus treating and preventing the recurrence of LBP.” (Teyhen et al., 2008; Axler & McGill, 1997).

The physiotherapists at Corona Station Physical Therapy recognize the importance of specific exercise prescription and a properly executed home exercise program to ensure optimal rehabilitation results. Time is spent educating the client as to the importance of the exercises they are given, while frequent review ensures proper exercise technique and allows for appropriate progressions. We believe it pays to be picky! For more information, please contact us at the clinic by phone or email and ask to speak to one of our physiotherapists.

Physical Therapy Management of Sacroiliac Dysfunction

Physical Therapy Management of Sacroiliac Joint (SIJ) Dysfunction

The sacroiliac joint (SIJ) is an often overlooked cause of mechanical low back pain.  SIJ dysfunction typically presents as pain over the posterior aspect of the joint. Pain may refer distally into the buttock and/or the lower extremity but rarely extends to the lumbar spine.  Weight bearing (walking, standing, stairs) can aggravate symptoms and turning in bed can also be problematic. Multiple causes of SIJ dysfunction include but are not limited to: scoliosis, leg length discrepancies, trauma, systemic processes, gait faults, pregnancy, weight gain and poor control of trunk musculature.

The primary role of the SIJs is to provide stability and to facilitate load transfer between the trunk and lower extremities.  Stability of the SIJs is determined by two primary mechanisms, form closure and force closure.  Form closure refers to the stability afforded by the anatomical design of the joint as well as the ligamentous/capsular support network.  The wedged position of the sacrum between the two innominates creates a “keystone like” design which is highly stable.  This is reinforced by the reciprocating grooves and ridges on the articular surfaces of the sacrum and ilia.  Strong SI ligaments aid load transfer between the trunk and the lower limbs.  Force closure is the stability imparted to the joint by the network of muscles which act across the joint.  These muscles can increase compressive load on the joint surface creating a high coefficient of friction thereby decreasing the potential for shearing. (Arumugam et al.; 2012) (Vleeming et al.; 1990).

 The muscle networks acting on the SIJs have been described as myofascial sling systems.  They include: 1) the posterior oblique sling comprised of the ipsilateral (same side) Glut Max, TFL, Biceps Femoris and contralateral (opposite side) Latissimus Dorsi; 2) the anterior oblique sling made up of the ipsilateral external oblique, internal oblique, TA and contralateral hip adductors; and 3) the longitudinal sling consisting of the multifidus (via attachment to the sacrum), deep layer of thoracolumbar fascia and long head of Biceps Femoris (attaching to the sacrotuberous ligament). (Vleeming et al.; 2012).

Various screening tests allow PTs to assess for the presence of SIJ dysfunction and evaluate how effectively the joint is stabilized during load transfer tasks.  Effective treatment of SIJ dysfunction includes biomechanical evaluation of the lumbar spine and hip to ensure adequate mobility of these adjacent regions, gait assessment, stretching exercises to address areas of poor flexibility and strengthening exercises to aid dynamic support.  Strengthening exercises can be started in non-weight bearing and progressed to weight bearing as symptoms and technique permit.  Soft tissue work +/- acupuncture can greatly facilitate the above measures in addressing muscle imbalances in the area.  SIJ taping and in some cases use of a SI belt, via increased passive stabilization and proprioceptive input to the area, can significantly decrease pain levels and increase tolerance for home exercise performance.  In cases of more marked SIJ instability, especially that of a structural nature, prolotherapy may be considered.

For further information, please call or email us to speak to one of our physiotherapists.

Gluteus Medius Weakness

Gluteus Medius Weakness

The Gluteus Medius

The gluteus medius is one of three gluteus muscles that originates on the posterior aspect of the pelvis and inserts into the lateral femur. It is know to abduct the hip and internally or externally rotate the femur depending on the position of the leg (1). More recently it has been shown to be an important muscle for stabilization, keeping the pelvis level and preventing internal rotation of the hip and the knee from buckling inward during weight-bearing.

This role as a muscle of stabilization has some important implications for injury prevention. Gluteus medius weakness has been linked to low back pain, patellofemoral pain syndrome, achilles tendonopathy and IT band syndrome(2,3). If a muscle of stabilization is weak or dysfunctional, it can lead to compensation from other muscles in the chain, leading to overuse injuries such as tendonitis.

A physical therapist can assess for gluteus medius weakness a number of ways, including testing the strength of abduction in side lying, testing internal rotation in sitting, or looking for a drop of the pelvis or Trandelenburg sign when an individual is standing on one leg. Once weakness in the muscle has been identified, the physical therapist can develop a specific exercise program to address the problem and prevent or rehabilitate an injury. Exercises may start with abduction or internal rotation in sitting or lying and progress to more functional activities in weight-bearing, including the activation of gluteus medius in combination with other muscles of the lower extremity as is typical of higher level activity such as sports.

For more information, please contact the clinic to speak with one of our experienced physical therapists.

References

1) Delp SLHess WEHungerford DSJones LCVariation of rotation moment arms with hip flexionJournal of Biomechanics 32 (1999) 493—501

2) Cooper NA1, Scavo KMStrickland KJTipayamongkol NNicholson JDBewyer DCSluka KAPrevalence of gluteus medius weakness in people with chronic low back pain compared to healthy controlsEur Spine J 2015 May 26

3) Fredericson, M, Cookingham CLChaudhari AMDowdell BCOestreicher NSahrmann SAHip abductor weakness in distance runners with iliotibial band syndromeClinical Journal Sport Med. 2000 Jul;10(3):169-75